Brazing Filler Material Research Articles

Deuterium permeation and retention behavior in copper-based brazing filler materials

Copper-based brazing filler materials are commonly employed in vacuum brazing techniques to achieve joining of plasma-facing components for ITER. In this work, gas-driven permeation (GDP) and thermal desorption spectroscopy (TDS) experiments have been performed to study the hydrogen isotopes permeation and retention behavior in two types of brazing filler materials (CuMnNi and CuGeNi metals). Experimental results show that CuMnNi filler exhibits the similar deuterium (D) permeability with CuMnNi filler but lower diffusion coefficients than CuGeNi filler. Three distinct peaks are observed between 380 K and 980 K for CuMnNi filler. However, no evident desorption peak is observed for CuGeNi filler. CuGeNi filler may be considered as a potential brazing filler material for reducing tritium inventory.

Interfacial structure between TiN sintered ceramics with and without an Fe-containing grain boundary phase and Ag–Cu eutectic brazing filler material

To focus on the interfacial reaction between the Ag–Cu alloy layer and TiN in active metal brazing, the Ag–Cu brazed interfacial structures between Cu and two types of TiN sintered ceramics fabricated by different methods were examined. No grain boundary phase components consisting of the Ni-containing Fe phase or Mo2C were detected on the TiN grain surfaces of the TiN liquid-phase sintered ceramic bonding surfaces before brazing. The brazed specimens were heated at 850 °C for 0.5 h. No Cu/TiN solid-phase sintered ceramic bonding was obtained. The Ag–Cu alloy layer was bonded onto the TiN grains in the TiN liquid-phase sintered ceramic through an Fe- and Ni-containing segregation layer. This segregation layer was formed by an interfacial reaction between the TiN grains and the Ni-containing Fe in the TiN liquid-phase sintered ceramic dissolved in the Ag–Cu liquid phase.

Investigation of Diffusible Hydrogen Concentration in Gas Metal Arc Brazing by Carrier Gas Hot Extraction Method Referring to ISO 3690

Arc brazing is an alternative joining technology well-suited for processing thermally sensitive materials and to produce mixed material connections. Due to the technological similarities of gas metal arc brazing to gas metal arc welding, it can be assumed that the process-related hydrogen input is of similar magnitude for both joining technologies. Since diffusible hydrogen is known to cause embrittlement in metallic materials, it is necessary to know the amount of diffusible hydrogen introduced by different manufacturing processes. Regarding the qualification of welding procedures, hydrogen ingress is an important factor to evaluate the risk of hydrogen-assisted cold cracking, especially when processing high-strength steels. For arc brazing, there is a lack of knowledge about the process-related hydrogen input. Hence, to study the influence of different brazing filler materials and varying levels of heat input on the diffusible hydrogen concentration in arc braze metal, a methodology to determine hydrogen content in arc weld metal in accordance with international standard ISO 3690 based on carrier gas hot extraction was applied to arc brazed specimens. Very low diffusible hydrogen concentrations of about HD = 0.1 to 0.3 mL/100 g were found for GMAB without significant influence of arc energy or filler metal used.

Development and characterization of Al-Si-Cu-Zn-Sn brazing filler alloy using vacuum arc furnace

Al-12Si filler alloy are used as brazing filler material for brazing titanium. In the present work, aluminium-based Al-12Si-xCu-0.5Zn-0.5Sn (wt %) (x = 0.5, 1, 1.5, 2) brazing filler alloys were developed using vacuum arc melting process. Structural characterization of the brazing filler alloy was done using XRD, Optical Microscopy and Differential Scanning Calorimetry (DSC). XRD results confirm the absence of intermetallic phases in the brazing filler alloy. Hardness measurement showed that hardness of alloy increases with increasing amount of Cu in the alloy with a maximum hardness of 86 HV. DSC analysis revealed a melting temperature of 570 ℃ of the Al-12Si-1Cu0.5Zn-0.5Sn alloy. Electrochemical behavior of the filler alloys were also studied.

A systematic study on the effect of coating type and surface preparation on the wettability of Si-Bronze brazing filler material on GI and GA-coated DP600

Zn-coated advanced high strength steels are popular in the automotive industry due to their excellent combination of mechanical strength and ductility as well as superior corrosion resistance provided by the Zn-coating – with hot-dip galvanized and galvannealed coatings being the most popular. Gas metal arc brazing technology is a non-fusion joining method, proposed as an alternative to the gas metal arc welding process due to several advantages: The arc-brazing process delivers significantly lower heat input to the substrate, which minimizes the Zn-coating burn-off leading to higher corrosion protection for the joined parts, and reduces the HAZ softening phenomenon which affects the mechanical integrity of the substrate, while at the same time reduces welding defects such as porosity and blowholes. The strength of an arc-brazed joint depends on the spreading of the molten filler material over the joint to create a bond between the parts as the molten braze solidifies. Existing literature on the subject suggests that heat input is the main driving factor controlling the wettability of the molten braze material with the type of shielding gas used also having an effect. However, the influence of different types of Zn-coatings and their respective surface condition (i.e., clean, or unclean) on the wettability of Cu-based molten braze materials during arc-brazing has not been investigated. The present work investigates the effect of surface morphology of galvanized and galvannealed DP600 steel in the as-received and plasma cleaned conditions on the wettability of molten Si-Bronze (CuSi3Mn1) brazing filler material in the bead-on-plate configuration. The findings of this work clearly demonstrate that the type of coating and its surface condition has a significant effect on the spreading of the molten filler material and on the growth of the intermetallic compound layer at the joint interface and therefore, should be taken into consideration as a factor that can impact the efficacy of an arc-brazed joint. • Evaluating surface morphology of different Zn-coatings to calculate their surface free energy. • Establishing a clear link between the surface roughness of Zn-coated steels on the wettability of molten Si-Bronze filler material. • The study shows that the wettability of the molten filler material is also affected by the presence of organic contaminants on the coating surface. • This work shows the relevance of surface morphology in controlling the wetting length of weld brazed joints. • The thickness of the intermetallic compound layer at the braze interface can be controlled by using oxygen plasma cleaning.

A review on filler materials for brazing of carbon-carbon composites

Abstract It is needed to join C/C composite to other materials since its individual use is limited. Brazing is a method to join C/C composite that has been studied most, maturest and most widely used in recent decades. The quality of a brazed joint is largely determined by the intermediate layer material. It is significant to choose filler materials reasonably. C/C composite is difficult to be wetted by common brazing filler materials. Moreover, there is a large difference in the coefficient of thermal expansion between C/C composite and metals. At present, there is no brazing filler alloy exclusively recommended for commercial C/C composites and metal brazing. Usually, active elements are added into filler metals to improve the wettability of them on C/C composite surface. The existing research includes Al-based, Ag-based, Cu-based, Ti-based, Ni-based brazing filler metals, and so on. In addition, various particle reinforced composite filler materials and stress buffer metal interlayer added composite filler materials have been studied for brazing C/C composite. The summarization of the overview on the application of intermediate filler metals is made in this paper. The basic reference basis is provided for the subsequent brazing filler metals development and joint performance improvement for C/C composite brazing.

TZM/graphite interface behavior in high-temperature brazing by Ti-based brazing filler materials

Graphite was successfully brazed to TZM alloy using the Ti-56Ni, Ti-8.5Si, Ti-33Cr and Ti-30V-3Mo brazing filler materials, respectively, and the corresponding brazing temperatures ranged from 1300 to 1700 °C. The results show that the microstructure of TZM/graphite braze metal was composed of NiTi and Ni3Ti compounds when using Ti-56Ni brazing filler, and the discontinuous TiC compounds were found at the Ti-56Ni/graphite side. When using the Ti-8.5Si, Ti-33Cr and Ti-30V-Mo brazing fillers, the metallurgical combination was obtained due to the formation of the Ti-Mo solid solution at the TZM/brazing filler side and the TiC reaction layer at the graphite/brazing filler side. The fracture was occurred at the interface of TiC/graphite during shear test, which indicated the poorer bonding strength between the graphite and granular TiC.

Design TiZrCuNi filler materials for vacuum brazing TA15 alloy

TA15 alloy with near α microstructure offers excellent high temperature mechanical properties for future gas turbine blades. To developing for the thin-wall and complex structure of this material, brazing is preferred. However, a new brazing material and process are required. In this study, a new theoretical modeling approach for designing Ti-based filler material for TA15 is presented by simulation on the bond strength in the crystal unit for the brazing filler material (BFM). The BFM chemical composition was determined as Ti-(17∼19)Zr-15Cu-15Ni wt.% to balance its strength, the toughness and relative lower melting temperature for TA15. All the fracture happened in the matrix rather than the brazing joints. It means that the strength of the brazed TA15 joint at room temperature was at least as strong as that of the matrix. Furthermore, under its service temperature (600℃), the strength of the brazing joint maintained almost 70 % of strength. The high joint strength and the ductile connection were attributed to the formed Widmanstätten structure and the sufficient diffusion of Cu and Ni solutes from the BFM across the interface. No intermetallics compound was formed in the joint. This model is established to optimizing a Ti-based filler material for achieving the excellent properties of brazed joints.

Current Review on the Research Status of Cemented Carbide Brazing: Filler Materials and Mechanical Properties

Cemented carbides have been widely applied in cutting tools and wear-resistant components due to their ultrahigh hardness and good wear resistance. However, the disadvantages of limited impact toughness and high cost have restricted their further application. Consequently, cemented carbides are usually joining with ductile steels to combine the advantages of both. Among various materials joining technologies, brazing have been an effective method to achieve high quality dissimilar cemented carbide joints. In this paper, the research status of cemented carbide brazing is reviewed. The materials utilized as brazing filler metal in cemented carbide brazing joints are summarized in detail. Researchers have done lots of works utilizing Cu based and Ag based brazing filler metals which are the most commonly used interlayers in brazed joints of cemented carbide and ductile steel. The effects of different filler metal on wettability, microstructure, phase constitution and mechanical properties of brazed cemented carbides joints are analysed. Besides, a series of newly developed brazing filler material such as nickel-based high temperature brazing filler metal, amorphous brazing filler metal and high entropy alloy brazing filler materials are also involved. These newly developed brazing filler metals have shown great potential in fabricating high quality joints. Finally, the current issues of cemented carbide brazing are reviewed and the develop trend is predicted.

Synthesis, characterization and welding property of micro-spherical molybdenum-ruthenium particles

Molybdenum-ruthenium powder is widely used as high-temperature brazing filler material. In this study, micro-spherical Mo-Ru particles were synthesized by spray drying combined with calcination technique from commercial (NH4)6Mo7O24 and (NH4)2RuCl6 powders. Micro-spherical (NH4)6Mo7O24 and (NH4)2RuCl6 mixture particles were achieved by spray drying treatment. The influences of calcination temperature on crystallization, morphology and size of as-synthesized Mo-Ru particles were investigated. The composition of as-synthesized Mo-Ru particles were Mo0.3124Ru0.6876 alloy and elemental Mo. Porous tungsten cylinders and molybdenum cylinders were welded together using the as-synthesized Mo-Ru powder. There was no any cracks around the welding region. The average tensile strength of welding samples was 76.65 ± 1.15 MPa. The results show that this is an excellent method to prepare molybdenum-ruthenium powder by spray drying combined with calcination. It should be noted that the powder technology in this study can be applied to synthesize other alloy powders (binary, ternary and more) with high-performance requirements.

Experimental thermodynamics, surface and transport properties of liquid Ag-Ge alloys

The aim of this study is to correlate the thermodynamics of liquid Ag-Ge alloys with their thermophysical properties such as the surface tension, viscosity, electrical resistivity and microscopic functions. For this purpose the Quasi-Chemical Approximation (QCA) for the regular solution and Faber-Ziman theory have been applied to describe the mixing behaviour of Ag-Ge melts in terms of the energetics and structure. Concerning the Ag-Ge system, the most important is Ag-24.5Ge (in at %) eutectic alloy, widely used as a brazing filler material. The melting temperature and the heat of melting of Ag-Ge eutectic alloy were measured by Differential Scanning Calorimetry (DSC). From a technological point of view, particular attention should be paid to the surface tension, a key property of the joining processes. Accordingly, the QCA and Butler’s model calculations have been done and subsequently, the model predicted values were compared to available literature data.

Effect of copper based filler composition on the strength of brazed joint

Vacuum brazing of copper-based filler was performed using pure copper plate as its based metal. The brazed joint was obtained at different temperatures, 680oC and 730oC, with same holding time, which is 30 minutes. MBF 2005 (Cu, 5.7wt.%Ni, 9.7wt.%Sn, 7.0wt.%P), MBF 2002 (Cu, 9.9wt.%Ni, 4.0wt.%Sn, 7.8wt.%P) and VZ 2250 (Cu, 7.0wt.%Ni, 9.3wt.%Sn, 6.3wt.%P) alloys were used as brazing filler materials. The intermetallic compound (IMC) and mechanical properties of the joints were investigated in detail. The result show that the interfacial microstructure of the brazed joints is Cu3P and (CuNi)2P. As the brazing temperature increase from 680oC to 730oC, the IMC become thicker leading to decrease in joining strength due to brittle IMC formation. The maximum shear strength reached 112 MPa at 680oC for MBF 2002 and 129 MPa at 730oC for MBF 2005. Hence, it is found that the composition of filler effects the strength of brazed joint.

Development of Metal Composite Powder Non-corrosive Flux for Low Temperature Forming of the Aluminum Brazing Filler Material

Development of Metal Composite Powder Non-corrosive Flux for Low Temperature Forming of the Aluminum Brazing Filler Material

Interdiffusion and microstructure evolution during brazing of austenitic martensitic stainless steel and aluminum-bronze with Ag-Cu-Zn based brazing filler material

Brazing of austenitic martensitic stainless steel (AMSS) with Al-bronze was carried out using Ag-26Cu-3.64Zn (wt%) as brazing filler material (BFM) and the interdiffusion behavior of various elements and microstructure evolution were investigated. Brazing was carried out at four different brazing temperatures (800, 820, 840, and 860 °C) for 15 min. It was found that in addition to increasing wettability of BFM, Ni-coating also plays a significant role in minimizing the loss of aluminum by diffusion from bronze side as well as in enhancing the joint strength. It caused partitioning of Cu and Zn from liquid BFM towards the base materials and formed (Cu, Ni) based solid solutions at the two interfaces. In addition, it reacts with aluminum from aluminum bronze to form intermetallic based on nickel and aluminum. In the joints brazed at 800 °C, continuous single phase layers were formed in the diffusion zone. However, at higher brazing temperatures, formation of multiphase zone was observed across the joints. Lap shear strength was found to be maximum in the joints prepared at 820 °C brazing temperature. Detailed mechanism behind the formation of different phases across the brazed joint and its correlation with joint strength are also presented.

Effect of filler wire composition on performance of Al/Galvanized steel joints by twin spot laser welding-brazing method

A twin-spot laser welding-brazing (LWB) process to join aluminum alloy 6022 and hot-dip galvanized steel in coach peel configuration was reported. A maximum surface roughness and sufficient mechanical strength are the important criteria which are affected by the process parameters during welding to judge the weld quality for some applications, such as the automotive industry. Thus, the influences of the main laser welding-brazing process parameters (laser power, wire feed rate, and scanning speed) on the mechanical strength and surface roughness of welds were studied and analytical models relating the output properties of interest to process parameters were also developed. The response surface methodology (RSM) and desirability function were utilized for optimizing the multi-response LWB process. Finally, validation experiments were conducted on an optimized process condition which exhibited good agreement between the predicted and experimental results. Four different filler wire materials were employed (AlSi12, AlSi5, AlSi3Mn1, and ZnAl15). The effects of the wire alloying elements on the microstructure of the weld, weld surface quality, and mechanical resistance were investigated. The measured intermetallic compound, IMC, layer at the Fe/Al interface of joints revealed that AlSi12 filler wire resulted in the thinnest IMC layer at less than 2μm; in contrast, this value increased to 7μm for joints with ZnAl15 wire. In terms of surface roughness, the lowest (Ra=0.917μm) and highest (Ra=2.83μm) values were achieved by using AlSi3Mn1 and ZnAl15 wires, respectively. Although the Zn-based filler wire offered the maximum tensile resistance around 180N/mm, joints with AlSi12 wire had mechanical resistance of 120N/mm and lower values of IMC layer thickness and surface roughness. Therefore, AlSi12 filler material is recommended as the laser brazing filler material for joining dissimilar aluminum-galvanized steel coach peel panels in automotive body-in-white (BIW) fabrication applications.

Effect of Copper-based Fillers Composition On Spreading and Wetting Behaviour

Wetting and spreading of molten brazing filler material are important factors that influence the brazing ability of a joint to be brazed. Several investigations into the wetting ability of a brazing filler alloy and its spreading area in the molten state, in addition to effects of brazing temperature on the contact angle, have been carried out. Generally, the composition of copper-based filler and temperature affect spreading of molten brazing filler material during brazing. Wetting by and interfacial reactions of the molten brazing filler material with the metallic substrate, especially, affect strongly the spreading of the filler material. In this study, the effects of filler composition and brazing temperature on the spreading of molten brazing filler metallic alloys were investigated. MBF 2005 (Cu, 5.7wt.%Ni, 9.7wt.%Sn, 7.0wt.%P), MBF 2002 (Cu, 9.9wt.%Ni, 4.0wt.%Sn, 7.8wt.%P) and VZ 2250 (Cu, 7.0wt.%Ni, 9.3wt.%Sn, 6.3wt.%P) alloys were used as brazing filler materials. Pure copper block and a rectangular plate were employed as the base metal. Brazing filler material and metallic base plate were first washed with acetone. Brazing was performed at 750°C and 800°C under Ar gas for 30 minutes using an electrically heated furnace, after which, the original spreading area, defined as the sessile drop area, and the apparent spreading area were both evaluated. It was observed that the spreading area and wetting angle influenced by the composition of copper-based filler.

Evolution of Microstructure in Brazed Joints of Austenitic-Martensitic Stainless Steel with Pure Silver Obtained with Ag-27Cu-5Sn Brazing Filler Material

Brazing of an austenitic-martensitic stainless steel (AMSS) with pure silver was carried out at 1053 K, 1073 K, and 1093 K (780 °C, 800 °C, and 820 °C) with Ag-27Cu-5Sn (wt pct) as brazing filler material (BFM). Wettability of the liquid BFM over base AMSS surface was found to be poor. Application of nickel coating to the steel was observed to enhance the wettability and to enable the formation of a good bond between BFM and the steel. The mechanism responsible for enhanced metallurgical bonding of the BFM with AMSS in the presence of nickel coating was explained based on diffusional interactions and uphill diffusion of iron, chromium and nickel observed in the brazed microstructure. Good diffusion-assisted zone was observed to form on silver side at all three temperatures. Four phases were encountered within the joint including silver solid solution, copper solid solution, Cu3Sn intermetallic and Ni-Fe solid solution. The Cu3Sn intermetallic was present in small amounts in the joints brazed at 1053 K and 1073 K (780 °C and 800 °C). The joint formed at 1093 K (820 °C) exhibited the absence of Cu3Sn, fewer defects and larger diffusion-assisted zone. Hardness of base AMSS was found to reduce during brazing due to austenite reversion and post-brazing sub-zero treatment for 2.5 hours was found suitable to recover the hardness.

The influence of Zr content on the performance of TiZrCuNi brazing filler

Brazing joining process offers a better structure integrity performance than traditional welding due to its lower melting point, considerable improved strength and narrower joining lines. It has been useful widely in aerospace industry for joining high-performance titanium alloys into a sandwich honeycomb structure, which enhances the weight reduction of aero vehicles. This research focuses on the effects of Zr content of the filler metal on brazing Ti-6Al-4V alloy sandwich structure as Zr was found to have profound influence on brazing performance e.g. brazing temperature, wettability and strength. Three different Zr content brazing filler materials were studied including two of them were designed. The associated joint tensile strength and microstructure by these three fillers were systematically evaluated. It is of interest to see that lower Zr content results in poorer brazing wettability while high Zr content leads to a reduction in strength due to the formation of interface compounds, which is an undesired phase lowering the toughness of joining. The appropriate Zr content (18wt%) is identified with an excellent combination of strength (22.3MPa), wettability and brazing temperature (1173K). A range of microstructure characterization tools including (SEM, TEM and EDX) were used to reveal the effect of Zr contents on local microstructure and explore the reasons for strength and wettability weakening.

Chemical elements diffusion in the stainless steel components brazed with Cu-Ag alloy

The paper presents the study of diffusion of chemical elements through a brazing joint, between two thin components (0.5mm) made of stainless steel 304. An experimental brazing filler material has been used for brazing stainless steel component and then the diffusion phenomenon has been studied, in terms of chemical element displacement from the brazed separation interface. The filler material is in the form of a metal rod coated with ceramic slurry mixture of minerals, containing precursors and metallic powders, which can contribute to the formation of deposit brazed. In determining the distance of diffusion of chemical elements, on both sides of the fusion line, were performed measurements of the chemical composition using electron microscopy SEM and EDX spectrometry. Metallographic analysis of cross sections was performed with the aim of highlight the microstructural characteristics of brazed joints, for estimate the wetting capacity, adherence of filler metal and highlight any imperfections. Analyzes performed showed the penetration of alloying elements from the solder (Ag, Cu, Zn and Sn) towards the base material (stainless steel), over distances up to 60 microns.

Joining Ti3SiC2 MAX phase with 308 stainless steel and aluminum fillers by tungsten inert gas (TIG)-brazing process

Herein we report on the Tungsten Inert Gas (TIG) brazing of Ti3SiC2 to 308 stainless steel and Al brazing fillers materials. The microstructures of the interfaces were investigated by scanning electron microscopy and energy dispersive spectrometry. Intensive interactions including dissolution and diffusion simultaneously occurred within the Ti3SiC2 and at the Ti3SiC2/308 stainless steel interface during TIG-Brazing. The interfacial region between Ti3SiC2 and 308 stainless steel filler is comprised of a decomposed Ti3SiC2 zone, an interaction layer zone and a modified 308 stainless steel zone. When the Ti3SiC2 comes into contact with the 308 SS molten filler during TIG-brazing, it starts decomposing into a TiCx+SiLiquid+Sigas, and simultaneously, deep penetration of the molten 308 SS into the Ti3SiC2 occurred to form a complex bright phase containing [Fe, Cr, Ni, Ti, C, Si] and TiCx phase. The loss of Si is attributed to its evaporation during the TIG-brazing process. Thermally induced residual stress due to thermal expansion mismatches create interfacial cracks between the decomposed Ti3SiC2 and the interaction layer zone. The phases that most likely form when Ti3SiC2 is joined with Al brazed filler material are Al in which some Si is dissolved, TiAl3 and Ti4AlC3. No cracks were observed during TIG joining of Ti3SiC2 with Al brazing filler material.